docs(api): hide 2.22 features from 2.21 docs (#17030)

# Overview

We cut the `[email protected]` tag from `edge` and it accidentally had some
stuff _from the future_ 🔮

This PR hides those things temporarily. We'll unhide them when writing
docs for the 2.22 release.

## Test Plan and Hands on Testing


[Sandbox](http://sandbox.docs.opentrons.com/docs-hide-future-2.22/v2/new_protocol_api.html)

## Changelog

- Exclude some methods in `new_protocol_api.rst`
- Turn some notes and deprecation notices in docstrings into invisible
comments, with TODOs to change back.
- Ran `black` on code files.

## Review requests

Check that there are no other mentions of 2.22. I've searched the source
(RST and Python) and can't think of anywhere they would pop up except
the API Reference page, which is clean now. I suppose there could be
some 2.22 stuff that wasn't tagged with a version and is still sneaking
through.

## Risk assessment

v low, docs only except whatever black did

api/docs/v2/new_protocol_api.rst

@@ -28,7 +28,7 @@ Labware
 =======
 .. autoclass:: opentrons.protocol_api.Labware
    :members:
-   :exclude-members: next_tip, use_tips, previous_tip, return_tips
+   :exclude-members: next_tip, use_tips, previous_tip, return_tips, load_empty, load_liquid, load_liquid_by_well
 
 ..
    The trailing ()s at the end of TrashBin and WasteChute here hide the __init__()

api/src/opentrons/protocol_api/instrument_context.py

@@ -763,8 +763,7 @@ def air_gap(
             ``pipette.air_gap(height=2)``. If you call ``air_gap`` with a single,
             unnamed argument, it will always be interpreted as a volume.
 
-        .. note::
-
+        .. TODO: restore this as a note block for 2.22 docs
            Before API version 2.22, this function was implemented as an aspirate, and
            dispensing into a well would add the air gap volume to the liquid tracked in
            the well. At or above API version 2.22, air gap volume is not counted as liquid
@@ -1604,9 +1603,11 @@ def transfer_liquid(
             source=[well._core for well in flat_sources_list],
             dest=[well._core for well in flat_dests_list],
             new_tip=valid_new_tip,
-            trash_location=checked_trash_location._core
-            if isinstance(checked_trash_location, labware.Well)
-            else checked_trash_location,
+            trash_location=(
+                checked_trash_location._core
+                if isinstance(checked_trash_location, labware.Well)
+                else checked_trash_location
+            ),
         )
 
         return self

api/src/opentrons/protocol_api/labware.py

@@ -292,7 +292,7 @@ def load_liquid(self, liquid: Liquid, volume: float) -> None:
         :param Liquid liquid: The liquid to load into the well.
         :param float volume: The volume of liquid to load, in µL.
 
-        .. deprecated:: 2.22
+        .. TODO: flag as deprecated in 2.22 docs
             In API version 2.22 and later, use :py:meth:`~Labware.load_liquid`, :py:meth:`~Labware.load_liquid_by_well`,
             or :py:meth:`~Labware.load_empty` to load liquid into a well.
         """